A capacitor is an element capable of storing electricity. Basically, two electrodes are opposed to each other, and when a voltage is applied, electricity is accumulated in each electrode. When a direct current (DC) voltage is applied, electricity is accumulated and current flows in the capacitor, but when accumulation is completed, no current flows in the capacitor. On the other hand, when an alternating current (AC) voltage is applied, AC current continues to flow, while polarities of the electrodes are alternately changed.
According to types of an insulator provided between electrodes, capacitors are classified as an aluminum electrolytic capacitor in which aluminum electrodes are configured and a thin oxide film is provided between the aluminum electrodes, a tantalum capacitor using tantalum as an electrode material, a ceramic capacitor using a high-k dielectric material such as barium titanate between electrodes, a multilayer ceramic capacitor (MLCC) in which high-k ceramics having a multilayer structure is used as a dielectric material provided between electrodes, a film capacitor using a polystyrene film as a dielectric material between electrodes, and the like.
The MLCCs, among the capacitors, which advantageously have excellent temperature characteristics and frequency characteristics and may be realized at a small size, have recently been commonly applied in various fields such as high frequency circuits.
In MLCCs of the related art, a plurality of dielectric sheets may be stacked to form a multilayer body, external electrodes having opposite polarities may be formed on an outer side of the multilayer body, and internal electrodes alternately stacked on an inner side of the multilayer body may be electrically connected to each of the external electrodes.
Recently, as electronic products have increasingly been miniaturized and highly integrated, research into miniaturization and high integration of MLCCs has actively been undertaken. In particular, in the case of MLCCs, various attempts have been made to improve connectivity of internal electrodes, while making a dielectric layer thinner, to stack more dielectric layers to increase capacity and reduce a size.
In particular, in the development of super-high-capacity MLCCs, ensuring reliability for multilayer products of thin dielectric layers and internal electrodes is becoming more important. As the number of stacked layers increases, a step increases due to a difference in thickness between the internal electrodes and the dielectric layers. Such a step causes ends of electrodes to be bent due to horizontal stretching of the dielectric layers during densification of pressing a body.
That is, the ends of the internal electrodes are bent to fill the step, and margin portions eliminate an empty space due to the step due to depression of a cover and a reduction of a margin width. A capacitive layer is also stretched by the margin width reduced as the empty space due to the step is eliminated. The structural irregular stretching of the internal electrodes results in a reduction of reliability such as breakdown voltage (BDV) characteristics, and the like, of an MLCC.
Generation of the step may be a problem in both a first direction perpendicular to a stacking direction of the MLCC and a second direction perpendicular to the stacking direction and the first direction, so a solution thereto is required.